Hi again guys,
Okay, I'm going to start my first recap of a mid 60's Motorola am radio.
From the schematic the radio calls for these caps:
2- 500uF/16v
1-10uF/25v
1-10uF/64v
1-1.6uF/25v
The one's that I have are as follows:
2-500uF/50v
1-100uF/50v
1-25uF/25v
1-2.2/50v
Will these work as substitutes (I hope)?
I also have the following just in case:
2-1000uF/25v
1-250uF/50v
I don't want to put the wrong values in and have problems so I'm putting it to you experts
I know there is a range variance and leeway here.
Any help would be appreciated.
Thanks !
Okay, I'm going to start my first recap of a mid 60's Motorola am radio.
From the schematic the radio calls for these caps:
2- 500uF/16v
1-10uF/25v
1-10uF/64v
1-1.6uF/25v
The one's that I have are as follows:
2-500uF/50v
1-100uF/50v
1-25uF/25v
1-2.2/50v
Will these work as substitutes (I hope)?
I also have the following just in case:
2-1000uF/25v
1-250uF/50v
I don't want to put the wrong values in and have problems so I'm putting it to you experts
I know there is a range variance and leeway here.Any help would be appreciated.
Thanks !
Hi,
You should stick to the original values until you know a bit more about their function in the circuit. The originals were chosen for a reason and you may end up with a non-working radio if you deviate from original spec.!
Your instincts are right. Some values can be more flexible than others but do you know which? I sure don't either!
The most important things to remember about caps:
Always check the polarity/orientation of electrolytic caps.
Always replace caps with the same or greater voltage ratings. You may end up seeing some smoke if these rules aren't followed.
Your 500uF caps are suitable because they are the same capacity and rated for a higher voltage. They might be physically larger though but you should be OK given the age of the original parts (probably large anyway).
Bottom line: Splash out on the proper parts and you will have a working radio for years to come.
Good luck,
Martin.
You should stick to the original values until you know a bit more about their function in the circuit. The originals were chosen for a reason and you may end up with a non-working radio if you deviate from original spec.!
Your instincts are right. Some values can be more flexible than others but do you know which? I sure don't either!
The most important things to remember about caps:
Always check the polarity/orientation of electrolytic caps.
Always replace caps with the same or greater voltage ratings. You may end up seeing some smoke if these rules aren't followed.
Your 500uF caps are suitable because they are the same capacity and rated for a higher voltage. They might be physically larger though but you should be OK given the age of the original parts (probably large anyway).
Bottom line: Splash out on the proper parts and you will have a working radio for years to come.
Good luck,
Martin.
Yes I think only one or two of your proposed replacements are suitable. It's OK to have more voltage, but the capacitance must always be the same.
Also, I'm a believer in if it aint broke don't fix it. I've plenty of ancient stuff that works fine and has been untouched since it was made. Is the radio showing signs of age in terms of it's performance?
Also, I'm a believer in if it aint broke don't fix it. I've plenty of ancient stuff that works fine and has been untouched since it was made. Is the radio showing signs of age in terms of it's performance?
Hi again guys and thank you for your advice. I appreciate it.
My understanding is that capacitance can be 20% lower and up to 100% greater than the specified value? I hear you on the voltage rating though. Don't want to go too low on that!
The 2.2uF/50v should work in replacement of the 1.6uF/25v shouldn't it?
Do the arrows on the caps indicate the + side ? The originals have a band designating + so I'm assuming (uh oh) that the arrows have replaced the "bands".
Any recommendations on a good supplier of caps?
The radio powers up but I only get static up and down the dial. I don't see that any of the original caps have leaked but have learned that leakage doesn't necessarily mean that the cap isn't dry inside.
Thanks once again,
Steve
My understanding is that capacitance can be 20% lower and up to 100% greater than the specified value? I hear you on the voltage rating though. Don't want to go too low on that!
The 2.2uF/50v should work in replacement of the 1.6uF/25v shouldn't it?
Do the arrows on the caps indicate the + side ? The originals have a band designating + so I'm assuming (uh oh) that the arrows have replaced the "bands".
Any recommendations on a good supplier of caps?
The radio powers up but I only get static up and down the dial. I don't see that any of the original caps have leaked but have learned that leakage doesn't necessarily mean that the cap isn't dry inside.
Thanks once again,
Steve
Capacitance tolerance can be quite wide, but I'd still try and stick to original values. They aren't hard to find. Banding usually indicates negative.
If you are only getting static I would guess the caps aren't going to help, they will be mainly for the audio output side of things, which seems to be working fine. My guess is a problem with the tuning circuitry or aerial.
If you are only getting static I would guess the caps aren't going to help, they will be mainly for the audio output side of things, which seems to be working fine. My guess is a problem with the tuning circuitry or aerial.
I suggest using 105C rated caps, and match the capacitance the best you can. In power supply circuits, you can usually go up a little bit, but don't double it or anything like that.
I also suggest putting in the highest voltage rating you can physically fit. Higher voltage ratings means higher ripple current capability, and longer life. Lower ESR, too.
I also suggest putting in the highest voltage rating you can physically fit. Higher voltage ratings means higher ripple current capability, and longer life. Lower ESR, too.
Sure. In environments where there is lots of heat, it's just better to use 105C.
Absolutely. Anything equal or greater in voltage is good. More voltage, the better (at least in power supply circuits, and IMO coupling too). What is more important is that you are equal or close in uF rating. Unless you know the circuit well, keep those the same.
65blkbkgt said:
you gotta be careful with the band designating its polarity. For the most part the band usually means negative. It may have rectangle type negative sign or <<< those going down the band. But i have seen the bands with + signs going down the side so be aware. Dont assume the band means positive cause most of the time its gonna mean negative.
there are allot of caps out there and good ones too. Dont get caught up spending $10-20 a pop. Panasonic, and nichicons have some good caps that arent priced so high.
I believe you have the following:
500 uF
10 uF
2.2 uF
All voltages are in excess of the as found caps. You should be good to go, as long as they physically fit. My guess is that the 1.6uF cap is a coupling cap; putting in the 2.2 will be of little consequence.
Can't DIY unless you actually "Do It"
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